In various surgical procedures and invasive investigations, it is necessary to gain access to the blood vessels (arterial or venous). Such procedures normally involve the percutaneous puncture of the artery (or the vein) so that an introducer can be inserted into the artery. This introducer consists basically of a hollow tube through which different medical instruments, such as catheters and tracers, can be inserted into the artery. Once the operation has been completed and the medical instrument has been removed, the introducer is removed, which leaves an opening in the artery through which blood would spurt unless certain measures are taken.
The most straightforward method to stop this bleeding is by the application of direct digital pressure over the puncture site by a trained physician or other suitably trained personnel. As an alternative, the direct pressure can be applied mechanically by a large clamp provided with pressure regulating means. The direct pressure method is associated with several drawbacks, the most important one being that the pressure has to be applied for a considerable period of time. In the case of punctures into femoral arteries, the pressure may have to be applied for as long as forty-five minutes for haemostasis to occur, which results in a substantial reduction of the flow of blood through the artery. Since thrombosis is one of the major complications that can occur in the immediate post-operative period, any reduction in the flow of blood through the arterial or venous system is highly undesirably.
A more sophisticated method for stopping the bleeding is by direct mechanical sealing of the puncture in the blood vessel. The sealing device may in this case consist of a first element to be placed at the inside surface of the vessel wall, a second element to be placed at the outside surface of the vessel wall, and a clamping member that holds the first and second elements together, thereby sealing the puncture in the intermediate vessel wall. Usually the clamping member also acts as a guiding member for the second element and extends to the outside of the skin surface. Examples of such sealing devices are disclosed in U.S. Pat. Nos. 5,350,399 and 5,620,461.
With such a device, the method with which the sealing device is arranged on both sides of the vessel wall will therefore, among others, comprise the following basic steps: The first element is inserted into the blood vessel by a pushing member. The pushing member and the first element are then retracted until the first element is seated at the inside surface of the blood vessel. Then, the pushing member is pulled back, and the second element, which is guided by the guiding and clamping member, is pushed forward until the second element is seated at the outside surface of the vessel wall. The first and second elements are now being held together by the guiding and clamping member, and the intermediate vessel wall is sealed. The part of the guiding and clamping member being on the outside of the skin surface can now be released, and the guiding and clamping member is severed at the level of the skin surface.
To manually carry out these and other operation steps needed to apply the sealing device obviously require a considerable amount of manual dexterity. Assuming that the guiding and clamping member is a thread, as disclosed in, for example, U.S. Pat. No. 5,620,461, which holds the first element in engagement with the inside surface of the blood vessel and along which the second element slides into engagement with the outside surface of the blood vessel, it is obvious that the thread has to be held tightly until the first and second elements have been tamped together. Furthermore, the force needed to push to the second element into position has to be carefully adjusted, so that the force is large enough to push the second element into contact with the outside of the vessel wall. However, measures must be taken so that this force does not push the second element too hard against the vessel wall, thereby penetrating the vessel wall and enlarging the puncture hole in the vessel wall. In order to facilitate some of the operation steps mentioned above, several types of insertion tools have been developed, see, for example, U.S. Pat. Nos. 5,350,399, 5,021,059, 5,441,517, and 5,282,827. The specific design and function of these different insertion tools will, of course, depend on the designs and functions of the corresponding sealing devices.
The present invention is directed to three of the operation steps mentioned above, namely: the retraction of the pushing member, the advancement of the second element into engagement with the outside surface of the vessel wall, and the release of the guiding and clamping member. These three operation steps will be referred to as the three inventive steps, in contrast to the operation steps included in the overall sealing procedure. Thus, the three inventive steps constitute a subset of the steps normally involved in the overall sealing procedure. Throughout the present application, the pushing member will be referred to as the pusher, and the first and second elements will be referred to as the inner seal and the outer seal, respectively. The guiding and clamping member consists in this case of a thread, which runs through a hole in the centre of the outer seal and is attached to the inner seal. During the first two inventive operation steps, the thread is tightened enough to hold the inner seal securely seated against the inside surface of the vessel wall. When the outer seal is pushed forward, it slides along the thread and is guided into engagement with the outside surface of the vessel wall. Once the outer seal is positioned correctly, frictional force arising from the fact that the diameter of the hole through the centre of the outer seal is slightly less than the diameter of the thread prevents the outer seal from moving back again. The second inventive operation step is herein referred to as the tamping step. Advantageously, the third inventive operation step is executed immediately after the two preceding steps. The designs and functions of these elements as well as the different operation steps and the requirements associated with them will be described in greater detail below.
Obviously, all inventive steps should be executed as smooth and precise as possible, in order to optimise the positioning of sealing device and minimise any risks of accidentally damaging the tissue. Consequently, a need exists for a device with which these steps can be executed in safe and consistent way. The device should be easy to handle, preferably with one single manual operation, and a completely satisfactory sealing of the vessel wall should be obtained each time it is used. Preferably, the device should be provided with a safety mechanism that prevents the accidental tamping of the outer and inner seals before the seals are correctly positioned at the respective sides of the vessel wall.